Don't waste your time on me

I am just curious as to why and how men can:

Text a woman constantly, sometimes for months on end, get to know her on a deeply intimate level, pursue her relentlessly, beg for her time and attention, look into her eyes while kissing her slow, hold her hand and then later say, "I'm just looking for sex right now."

Why do you guys do that to women and to yourselves? You do realize there ARE women out there who will simply have sex with you in a FWB type arrangement, right? Plenty of them, in fact. No need to deceive.

Honestly, I just don't see how colossally wasting your own AND someone else's time is fruitful, in the long run. So, you got laid. Great. Well, now that she knows your intentions, you're not getting it from her again. So, you've got to start over with your prowling and your coaxing. Seems exhausting.